The objective of the proposed research is to establish human B-cell lines that secrete monoclonal antibody to the human tumor antigen, OFA-I (Oncofetal Antigen-Immunogenic). During the first year of this research, we reported successful in vitro production of IgM anti-OFA-I antibody from blood\B lymphocytes transformed by Epstein-Barr virus. Two long-term cell lines, L72 and L55, were established. Although the two antibodies produced by these lines both react to OFA-I positive human cancer tissues, they differ in their reactivity pattern against certain human tumor cells. Antibody produced by the L55 cell line reacted to an antigen (OFA-I-1) expressed on a variety of cancer tissues. On the other hand, antibody produced by the L72 cell line only reacted to an antigen (OFA-I-2) on tumor cells of neuroectodermal origin. For the past year, two major accomplishments were made: (1)\OFA-I-1 and OFA-I-2 antigens and antibodies were characterized biochemically; and (2)\a new line, L61, that secreted an additional antigenic specificity was established. A difficulty of this research is that secretion of antibodies from EBV-transformed lymphoblasts has been limited in terms of the amounts and periods, which largely has prevented their use in further characterization of the antigen and antibodies, in particular for the clinical application. Therefore, the goal set for the current year is: (1)\to establish new lymphoblastoid cell lines that produce higher titer antibodies by preselecting specific B lymphocytes before EBV transformation; (2)\to clone L55 and L61 sublines that produce anti-OFA-I for a longer period; (3)\to augment antibody production of the anti-OFA-I cell lines by hybridoma techniques; (4)\to characterize antibodies secreted from the new line, L61; and (5)\to search for additional antigenic specificities with new human B-cell lines.